A few questions about Progressive Interlaced and deinterlace method

I have a video project with mostly progressive source material and a little bit of interlaced source material. My final render will be just for playback on my laptop and sometimes I'll put the file on my flash-drive to plug into my widescreen vizio hd tv through the usb port for viewing. I don't plan on making dvds and my footage will be 25fps ad the final render will be 854x480 or sometimes my renders will be 1280x720.

I read somewhere that "If you deinterlace a video which is not interlaced, then the result is worse than the source."

1.) So If most my source material is already progressive and I want the best quality possible should I set the field order to none progressive and leave the deinterlace method to none or should I still set a deinterlace method?

2.) Also which do you think is better for sports videos? Blend fields or Interpolate?

3.) And if my project source material is all interlaced and I want it rendered deinterlaced should I:

a. choose "lower field first" as field order and then set a deinterlace method

or

b. choose none progressive scan and set a deinterlace method (blend or interpolate)

[Tony Frank]"1.) So If most my source material is already progressive and I want the best quality possible should I set the field order to none progressive and leave the deinterlace method to none or should I still set a deinterlace method?"

You always want to set a deinterlace method. This is only used for interlaced footage and will be ignored for progressive footage.

[Tony Frank]"2.) Also which do you think is better for sports videos? Blend fields or Interpolate? "

Interpolate will be better for fast moving sports.

[Tony Frank]"3.) And if my project source material is all interlaced and I want it rendered deinterlaced should I: a. choose "lower field first" as field order and then set a deinterlace method or b. choose none progressive scan and set a deinterlace method (blend or interpolate) or c. choose none progressive and leave deinterlace method to none"

The best answer is B. If you know you are going to deliver progressive, you should set your project to progressive so that any titles or other generated media that you add will be created as progressive. Setting the deinterlace method will take care of deinterlacing your interlaced footage when it comes time to render.

Thanks for the reply John. I appreciate it.
I'm making a soccer video.

"Always set deinterlace method. This is only used for interlaced footage and will be ignored for progressive footage"

I'll take your word for it.

And sorry just 3 more questions.

1.) Should I disable resample always for progressive and interlaced video? Does disabling the resample have an affect on the deinterlacing and the quote above?

2.) If I have both progressive and interlaced footage and I choose Progressive field order, set deinterlace method to none, and render as progressive main concept mp4 file will the Interlaced footage become worse or stay the same as if its being rendered interlaced?

3.) What if I'm using all progressive source material for my project? Then is it necessary to set a deinterlace method? Or should I just set it to none and then the field order to progressive.

[Tony Frank]"1.) Should I disable resample always for progressive and interlaced video? Does disabling the resample have an affect on the deinterlacing and the quote above?"

The only reason to disable resample is if you are seeing ghosting on your frames. This will happen sometimes when the framerate of your footage does not match the frame rate of the project. For example when you have video that is 60 fps and you are delivering 30 fps because Vegas Pro isn't smart enough to drop every other frame to go from 60 to 30 so it blends the frames together and makes a mess. If, however, your footage is 30 fps and you are delivering 24 fps you probably want to leave resampling on so that it does blend the frames to make new ones.

Disabling resample has nothing to do with deinterlacing.

[Tony Frank]"2.) If I have both progressive and interlaced footage and I choose Progressive field order, set deinterlace method to none, and render as progressive main concept mp4 file will the Interlaced footage become worse or stay the same as if its being rendered interlaced?"

The interlaced footage will look much worse and be unwatchable. This is because you can't render interlaced footage as progressive without deinterlacing, and since you told Vegas Pro not to deinterlace it just makes a big mess out of the video.

[Tony Frank]"3.) What if I'm using all progressive source material for my project? Then is it necessary to set a deinterlace method? Or should I just set it to none and then the field order to progressive."

It is not necessary to set a deinterlace method of you have no interlaced footage on your project and you project is set to progressive, however, it will not harm anything if you do set a deinterlace method so I strongly recommend that you leave the deinterlace method set to the default which is Blend Fields unless you have a reason to change it because of you forget to change it back for the next project and you use interlaced footage you will have a mess.

The deinterlace method is Vegas Pro's way of saying: "If there is interlaced footage in the project and I find the need to deinterlace it to apply FX, which method would you like me to use?". Read that again because it doesn't only affect renders, If you add any plug-in FX to interlaced video and you did not set a deinterace method, you will get a mess because most plug-ins require deinterlaceds footage in order to work.